1. Field of the Invention
This invention relates generally to a method and apparatus for shrinking skin tissue without damaging the melanocytes and other epithelial cells, and more particularly to a method and apparatus that creates a reverse thermal gradient in order to achieve skin tightening through partial denaturation of collagen without ablation of the collagen and without affecting the melanocytes and other epithelial cells.
2. Description of Related Art
The skin is the one organ of the body that is readily available for inspection by the eyes and fingers of every living person. It is subjected to considerable abuse such as exposure to extreme environmental of cold, heat, wind, and sun.
The surface layer of the skin is called the epidermis. It is the barrier that prevents most substances from entering the body from outside while preventing body fluids from entering equilibrium with the environment. The basilar layer of the epidermis includes the melanocytes and other epithelial cells.
The melanocytes are small cells with a small, dark staining nucleus and a clear cytoplasm. Melanin packaged in distinctive granules is produced by these cells and transferred to air dendritic processes to adjacent keratinocytes. The purpose of melanin is to protect the skin from the ravages of ultraviolet radiation. Beneath the epidermis is the papillary dermis and reticular dermis. Collagen tissue is found in the dermal and the sub dermal tissues.
There has been a large market for tightening the skin in order to reduce aging effects and effects created by exposing the skin to extreme environmental forces. To date there are two primary methods for tightening skin. The first is surgical skin excision. The second is chemical burn. When skin is surgically excised it leaves large scars. This is generally not a satisfactory solution for many skin tightening applications. With chemical peel treatments the process is painful, there is damage to the melanocytes and other epithelial cells, the patient may have spotted pigmentation, or with most of the melanocytes and other epithelial cells destroyed the patient can have a predominately white complexion. In the chemical peel method a thermal gradient is created which is hotter at the surface of the epidermis and cooler at the sub dermal layers. With the creation of this type of thermal gradient there is a great likelihood of modification or destruction of the melanocytes and other epithelial cells, resulting in blotchiness or an inability to tan in the future.
Collagen molecules are produced by fibroblasts which synthesize three polypeptide chains that wrap around one another in a triple helix. Each of the chains is approximately 1000 amino acid units in length, with glycine recurring regularly every third unit and hydroxyproline and proline recurring very frequently. Cross-linking occurs between the side, not the ends, of collagen molecules and is coupled with the amino acid composition to give collagen its great strength. Collagen tissue shrinkage takes place in a direction parallel to an axis of collagen fibers.
The phenomenon of thermal shrinkage of collagen begins with a denaturization of the triple helix of the collagen molecule. Partial denaturization of collagen tissue results in a shrinkage of the collagen and provides a "tightening" effect on the overlaying skin. To date there have been no devices or methods for contracting the underlying collagen tissue through partial denaturization without damaging the melanocytes and other epithelial cells in the epidermis.
Adipose tissue, more commonly known as fat, is formed of cells containing stored lipid. Adipose tissue is often subdivided into small lobules by connective collagen tissue serving as the fibrous septae.
Adipose tissue is widely distributed in the subcutaneous tissue but exhibits regional differences in amount partially because of age and sex. Excess adipose tissue can be physically undesirable from both health and cosmetic perspective. A current method for the removal of fatty tissue is the extraction of adipose tissue by liposuction. This is a purely mechanical method with undesirable side effects due to the invasive nature of the process.
Another method of removing fatty tissue is disclosed in U.S. Pat. No. 5,143,063 ("the '063"). The method of the '063 patent targets adipose tissue that absorbs sufficient energy resulting in cell destruction and death. The method of the '063 patent fails to minimize damage to the melanocyte in the epidermis. Thus, the method of the '063 patent can create unwanted blotchiness or changes in the melanocytes and other epithelial cells.
There exists the need for skin tightening without damaging the melanocytes and other epithelial cells, or without surgical intervention. There is a further need for non- surgically removing adipose tissue without damaging the melanocytes and other epithelial cells.